Dec 17 2019

Where is Fusion?

The promise of commercial-scale fusion energy has been looming in the background of our collective conversations about climate change and the future of our energy infrastructure. The potential of fusion is tremendous, but we are likely still decades away from commercial power plants. Exactly how far away is a matter of debate. There are some indications, however, that the industry is progressing from proof of concept research to commercialization. No one is seriously arguing that we are close, but this may be a sign of real progress.

Fusion energy is the energy that powers the sun. It comes from fusing light elements into heavier elements, starting with fusing two hydrogen atoms into one helium atom. You can get net energy out of fusing light elements, all the way to iron. Iron requires energy to either fuse or to undergo fission, and so that is the end of the line in terms of energy production. The heavier the element, the more pressure and heat it takes to fuse. All suns start our fusing hydrogen into helium, by definition. Once the hydrogen fuel is burned, suns that are sufficiently massive will contract, increasing their temperature and pressure, until their helium core starts to burn. More and more massive stars can fuse more and more heavier elements. The most massive stars can fuse lighter elements into iron, and then, as stated, that is as far as they can go.

Here on earth researchers hope to build devices that create sufficient heat and pressure to fuse hydrogen into helium. Deuterium and tritium (isotopes of hydrogen with one and two neutrons respectively) are easier to fuse, so that is what is being used. The advantage to a successful fusion reactor is that the conversion efficiency of fuel into energy is tremendous, greater than fission. Only matter-antimatter annihilation can produce more energy for a given mass. Further, fusion produces no long-lived nuclear waste, and releases no carbon or other pollutants. The end product is helium, which is a useful element. Tritium itself is radioactive, but very short-lived. Also, the containment vessels will become bombarded with neutrons, and it remains to be seen what technologies will be used to protect the structure.

So how close are we to building a commercial plant capable of producing significant net power? Well, some research fusion reactors have caused fusion, and some have even produced more energy than they consume for short periods. So we are basically at the proof-of-concept stage. Often news reports tout such proofs-of-concept as if they are the only breakthrough needed, and then gloss over the need to scale up to commercial applications as if that is an afterthought or a foregone conclusion. Scaling up to commercial use is where many new technologies fail, and is not a trivial step.

With fusion no one has yet built a commercial scale prototype plant. So first they have to demonstrate that the technology will work at that scale. But perhaps more importantly, what will be the upfront cost and what will be the cost of the electricity produced over the lifetime of a fusion plant? The cost efficiency of such plants will be determined partly by their efficiency – how much net electricity do they produce – and their durability. Durability is a significant concern, given the extreme conditions needed for operation. The bottom line is that commercial viability is still the big question mark.

A recent article in Business Insider may, however, provide some hopeful signs. In fact, business articles may be more telling than scientific papers when considering the viability of fusion. The article reports that Jeff Bezos and other investors have just raised $65 million in a round of fundraising for a specific fusion technology company, General Fusion. There design is different than the most common tokamak design, which is similar to a doughnut shape. The General Fusion design is spherical, with hydrogen gas in the middle surrounded by a shell of flowing liquid metal. Around that is arranged a serious of pistons (300 pistons in the proposed design for a commercial-scale plant). The pistons are meant to fire all at once, squeezing the liquid metal and thereby compressing the hydrogen gas in the core to the point of fusion. The fusion will produce excess heat, which will be used to create steam, to run a turbine, and produce energy similar to most power plants. The proposed plant design would produce about 100 megawatts of capacity.  (The largest nuclear fission reactor in the US has a capacity of almost 4,000 MW.) Current wind turbines have capacities of 2.5-3 MW.

The $65 million is about a third of what is needed to build a prototype commercial plant. But really, the consensus seems to be that billions of dollars will be necessary to fully develop and build commercial-scale fusion power plants. The BI article indicates that investors are starting to take interest in fusion power, and that the industry is turning from basic research to developing commercial scale plants. This is an encouraging shift, and may indicate that the industry is ready to transition to the next phase.

But skeptics remain, and they argue that the relatively small amounts investors have so far been willing to put into fusion power is indicative that the technology is not yet ready to become commercially self-sufficient. We are still in a phase where large governments need to drop billions of dollars on R&D before private investors will be drawn into the industry.

The IAEA believes that the ITER nuclear fusion project could build a prototype small commercial plant by 2040, which is the earliest estimate I am seeing. This likely means that actual functional plants will not come online before 2050-2060, and that is being optimistic. Even in an optimistic scenario, it will be 50-60 years before a significant amount of our energy infrastructure is produced by fusion. So realistically, we cannot wait for fusion to solve our energy problems. We need to proceed as if fusion will not happen anytime soon. Even if we anticipate it by the 21st century, we need an energy plan for this century.

One open, and important, question is this – how much can we accelerate this timeline if governments infuse massive resources into the industry. If the US, for example, dedicated tens of billions of dollars to fast-tracking nuclear fusion, how soon could we realistically have operational plants? From everything I am reading, it seems realistic that such massive investment could bring the realization of fusion power decades earlier than without such investment. How much will those decades be worth? I’d like to see some hard numbers, but I would not be surprised if the investment was worth it by a large margin. If we consider all the downstream benefits – environmental, health, and mitigating climate change – this may be an infrastructure investment that pays for itself many times over.


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